Units of coiling material strips are currently found in steel mills, particularly in association with rolling equipment. Such units may involve only a single strip of relatively great width to be coiled or, when a machine for splitting already rolled sheet is present, they may involve the coiling about the same coiling shaft of several tight coils coming from the same mother strip cut lengthwise. As will be seen below, this second application raises particular problems that the present invention particularly proposes to solve.
In the known method, at the end of an operation of coiling one or more metal strips, an operator stops the machine and temporarily immobilizes the strip tail on the coil which has just been made, for example, by a piece of adhesive tape, to facilitate removal of the sheet coil to the packaging station. Even in the simplest case where a single strip is wound on the shaft of the machine, this operation represents considerable idle time in the use of the machine. In case the coiling occurs after splitting, this idle time is accompanied by a considerable waste of sheet at the end of the coiling. Actually, a mother strip at the output of the rolling does not have a constant thickness over its entire width. In brief, it is said that a rolled strip has "long edges" if the thicknesses at the edges are thinner than the thickness at the center and that it has a "long center" in the opposite case. Thus, strips cut from a mother strip with "long edges" and coiled on the same shaft of a coiling machine give rise to coils of different diameter that are greater in the middle of the coiling shaft than at its ends, an opposite situation being created by starting with a mother strip with a "long center". Under these conditions, from a given lengthy mother strip, the tails of the split strips will be in various positions in relation to one another at the end of the common coiling. To avoid having to immobilize the strip tails one after the other as they reach the coiling machine, by making the latter advance manually step by step, it is generally preferable to stop the machine when the first sheet tail reaches it and to cut all the other strips to the same length, at that time, to immobilize only one time the new strip tails thus created on their respective coils and then to unload the machine. This therefore involves a loss of a certain length of the split strip.
To momentarily immobilize the strip tails, there is known an adhesive tape device provided with supports that carry a roll of adhesive tape and a swinging roller intended to press the tape on a coil of strip material (U.S. Pat. No. 3,869,845). However, the means used in this device are not effective and do not make it possible to obtain successive automatic immobilizations of strip ends on industrial installations.